1. Field of the Invention
This invention relates to a contact adhering method, in which adherends are fastened by means of an adhesive which does not contain any solvent and can be cured without any heating process.
2. Description of the Related Art
Conventional solvent-based elastomeric adhesives (rubber cement) are easy to use to fasten adherends, since these adhesives do not require that adherends be temporarily kept pressed until they are firmly fastened, and since it is possible to let a certain period of time (open time) pass before the adherends must be fastened. However, such elastomeric adhesives include solvents as indispensable components, which are toxic to man and are flammable.
Various efforts and research have been carried out to solve the above inconveniences of the conventional solvent elastomeric adhesives through such alternatives as (1) high solidification, (2) non-use of solvents, and (3) use of aqueous contact (aqueous emulsion type) adhesives. However, these alternatives are not satisfactory for the following reasons.
(1) When it is highly solidified to remove the solvent, the adhesive cannot maintain its effective adhesiveness. (2) Use of hot melt adhesives is conceivable in place of the solvent adhesives. The hot melt adhesives are easy to use, but should be heated and are difficult to apply to large adherends. (3) Aqueous adhesives are safe from the viewpoint of hygiene and non-flammability, but have low contact adhesiveness. The aqueous adhesives are applicable only to water-absorbing adherends such as wood, and take time to dry.
With a conventional adhering method using a moisture curable type adhesive, the adhesive is applied on a single one (single spread) or both (double spread) of the adherends, and the adherends are fastened to cure the adhesive. In such a case the adhesive is slow to cure. Even when the adhesive is applied to adherends having a good moisture permeability, it will take one or two days for adhesive to cure at room temperature. In addition, the adherends have to be temporarily fastened by some means. This means the adhering task is very troublesome. When fastening adherends having no moisture permeability such as steel sheets, the adhesive takes time to cure, which makes the task even more troublesome.